This invention relates to a novel copolymer of a fluorine-containing methacrylate with styrene or its derivative and a method of preparing the same.
Functional polymers of fluorine-containing methacrylic or acrylic esters are attracting increasing interest. Such polymers are expected to have wide applications such as, for example, textile oil using the water- and oil-repelling property attributed to fluorine, fluororubbers using the chemical resistant property, optical plastics using the low refractivity characteristic, resist materials and dental materials. In fact, considerable items have already been developed to the stage of practical applications.
Until now, the aforementioned polymers are mostly of a group of fluorine-containing methacrylates represented by the general forumula (A): ##STR1## wherein R is hydrogen atom or methyl group, and R' is a partly fluorinated alkyl group. That is, methacrylates having fluorine atoms in the ester group are used. For example, copolymers of a methacrylate containing a perfluoroalkyl group in the ester group with an aliphatic monomer are widely used as water- and oil-repelling agent for treatment of textile.
Another group of fluorine-containing methacrylates represented by the general formula (B), viz. .alpha.-trifluoromethylacrylates, are expected to provide functional polymers having unique characteristics. ##STR2## wherein R represents an alkyl group or a fluorine-containing alkyl group.
However, monomers of the general formula (B) cannot freely be polymerized. As reported, for example, in Macromolecules, 15. 915 (1982), these polymers can be polymerized by anionic polymerization using pyridine or n-butyl lithium as initiator, but cannot be polymerized to homopolymers by radical polymerization using a common initiator such as benzoyl peroxide. The same reference reports that radical copolymerization of methyl .alpha.-trifluoromethylacrylate with methyl methacrylate is possible but requires a very long reaction time for obtaining a copolymer containing a relatively large amount of the fluoroacrylate with good yield.